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Educator and Tagging Information Learning Area: Technology Resource Name: Technology Assessment Exemplar Number: TECHN9.106 Item/s: 1 Phase: Senior Phase Grade: 9 Tags: Technology, systems and control, electrical systems, electronic circuits, output, input, Ohm’s law, relationship, potential difference, current, resistance, electrical circuit, calculations, worksheet, Formative Assessment Assessment Type: Formative Assessment Form/s: Worksheet Copyright for included material: N/A Duration: 60 min Learning Outcome(s) and Assessment Standard(s): Learning Outcome 2: Technological Knowledge and Understanding The learner will be able to understand and apply relevant technological knowledge ethically and responsibly. Assessment Standards We know this when the learner 3 Systems and Control 3.2 Demonstrates knowledge and understanding of how simple electronic circuits and devices are used to make an output respond to an input signal (e.g. resistors, light-emitting diodes, transistors, push or magnetic switches, thermistors, light-dependent resistors). Learning Space: Assessment Hyperlinks: To be completed later. Rating: Number of questions for exemplar: 1 Easy questions: Medium questions: Difficult questions: Question 1 Assessment Task Ohm’s Law calculations State Ohm’s Law. [2 marks] Explain the relationship between the potential difference, current and resistance in an electric circuit. [6 marks] 1.3 Use Ohm’s Law to calculate the following answers: 1.3.1 Calculate the resistance across the filament in a lamp with a current of 0,5 A when it is connected to a supply of 220V. [3 marks] 1.3.2 A lamp operates from a 220V supply. The resistance is 550Ω. Calculate the strength of the current when it is lit. [4 marks] 1.3.3 An electronic circuit needs a potential difference of 3,6V across a resistor when a current of 30mA is in it. Would the voltage be 3,6V if the resistor had a resistance of 96Ω? [5 marks] [25 marks] 1.1 1.2 Suggested Solutions Question number 1. Possible marks 2 marks 6 marks 3 marks Answers 1.1 Ohm's law says that in an electric circuit, the current passing through a resistor between two points is related to the voltage difference between the two points and inversely related to the electrical conductance between the two points. 1.2 When the potential difference (voltage) increases, the current also increases. All conductors of electricity have some resistance to current. If the resistance in a circuit is increased, the current will be decreased. 1.3.1 V = 220V I = 0.5A R = x V I 220V R 0.5 A R R= 440Ω 3 4 marks 1.3.2 V = I R 220V = x = 550Ω V R 220V I 550 I I= 0.4A 4 There are various ways of working out the answer. For example: V = x I = 30mA (30mA ÷ 1000 = 0.03A) R = 96Ω V=IxR V = 0.03A x 96Ω V = 2.88V Answer: No, the voltage would be 2.88V and not 3.6V. [25 marks] Appendix of Assessment Tools 5 marks 1.3.3